The present invention generally relates to chucks for use with drills or with electric or pneumatic power drivers. More particularly, the present invention relates to a keyless chuck that may be tightened or loosened by hand or by actuation of the driver motor. The keyless chuck of the present invention has particular applicability with hammer-type drills or drivers.
Both hand and electric or pneumatic tool drivers are well known. Although twist drills are the most common tools used with such drivers, the tools may also comprise screwdrivers, nut drivers, burrs, mounted grinding stones, and other cutting or abrading tools. Since the tools may have shanks of varying diameter or the cross-section of the tool shank may be polygonal, the device is usually provided with a chuck that is adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore.
A wide variety of chucks have been developed in the art. In the simplest form of chuck, three jaws spaced circumferentially approximately 120 degrees apart from each other are constrained by angularly disposed passageways in a body attached onto the drive shaft and configured so that rotation of the body in one direction with respect to a constrained nut engaging the jaws, forces the jaws into gripping relationship with the cylindrical shank of a tool, while rotation in the opposite direction releases the gripping relationship. Such a chuck may be keyless if it is rotated by hand.
Despite the success of such keyless chucks, varying configurations of keyless chucks are desirable for a variety of applications. In particular, it is desirable to provide a chuck for use in a hammer drilling application. In a conventional chuck used for hammer drilling, the vibration that results from use of the tool can cause the jaws to loosen their grip around the shaft of the tool. This can have undesirable consequences, both for the work piece and for the operation of the tool.
One solution to that problem is proposed in U.S. Pat. No. 5,816,582. In that patent, however, the chuck requires a front sleeve that has a number of ribs and indentations that may increase the cost and complexity of the chuck. Accordingly, it would be desirable to provide a keyless chuck that requires fewer components and/or lower manufacturing cost.